Creatine is synthesized in the liver and kidney and transported throughout the body to tissues with high energy demands through an active transport system. Creatine is used by the body during times of increased energy demands to rapidly resynthesize ATP from ADP through the anaerobic conversion of phosphorylated creatine (phosphocreatine) to creatine in a reversible reaction by the enzyme creatine kinase. In times of low energy demands, excess ATP can be utilized to convert creatine to phosphocreatine. Increased expression of creatine kinase promotes metastasis by enhancing the survival of disseminated cancer cells in the liver where they encounter hepatic hypoxia. Increased expression of creatine kinase results in production of excess phosphocreatine which may be used as an energetic store for generating ATP needed to endure hepatic hypoxia. Inhibition of the phosphocreatine system through inhibition of creatine uptake and/or creatine kinase in cancer cells is thus a therapeutic target for the treatment of cancer and/or metastasis.